1. Field of the Invention
The present invention relates to an imaging apparatus which acquires an image of an object by receiving light from the object and performing a photoelectric conversion, and a method of manufacturing the imaging apparatus.
2. Description of the Related Art
Conventionally, a small imaging apparatus is proposed for incorporation into digital cameras, video cameras, and portable terminals such as mobile telephones and Personal Digital Assistants (PDA) provided with a function of camera. The imaging apparatus acquires an image of an object by receiving light from the object and performing photoelectric conversion of the received light. Such an imaging apparatus includes a solid-state imaging sensor such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) image sensor, and an optical system which focuses light from the object on a light receiving surface of the solid-state imaging sensor to form the image (see, JP-A No. 2003-110945 (KOKAI), for example).
In recent years, such an imaging apparatus has come to be incorporated into medial devices such as endoscopes and capsule endoscopes. These medical devices are employed for observation of an inside of alimentary tracts of a subject, for example. Therefore, further downsizing of the imaging apparatus is highly desirable. For the downsizing, the imaging apparatus is formed of a chip-size package (CSP) type solid-state imaging sensor. The CSP is a package of substantially the same outer dimension as a semiconductor chip. FIG. 8 is a schematic cross-sectional view showing a side cross section structure of a conventional imaging apparatus including such a CSP-type solid-state imaging sensor
As shown in FIG. 8, a conventional imaging apparatus 101 includes a CSP-type solid-state imaging sensor 102 which has a light receiving unit 102a for reception of light from an object, an optical system 103 which focuses light from the object on a light receiving surface of the light receiving unit 102a, a circuit board 104 on which the solid-state imaging sensor 102 is mounted, and a resin material 105 which reinforces the packaging strength of the solid-state imaging sensor 102 and the circuit board 104. The solid-state imaging sensor 102 has a cover glass 102b which protects a semiconductor chip (CCD chip, for example) on which the light receiving unit 102a is formed, and solder balls 102c. The optical system 103 includes a lens 103a which focuses light from the object onto the light receiving unit 102a, a barrel member 103b which protects the lens 103a and delineates a light receiving region 103d on a surface of the cover glass 102b, and a light blocking wall 103c which shields a region outside the light receiving region 103d of the cover glass 102b from light. The barrel member 103b has a through hole inside. An opening at one end of the through hole is closed by holding the lens 103a, whereas an opening at another end of the through hole delineates the light receiving region 103d on the cover glass 102b at a position corresponding to the light receiving unit 102a. The light blocking wall 103c has a substantially reverse-U-shaped cross section. The light blocking wall 103c engages with the cover glass 102b so as to cover a region (upper surface and side surfaces of the cover glass 102b) other than the light receiving region 103d of the cover glass 102b. 
When the imaging apparatus 101 is employed for imaging of the object, light from the object comes into the barrel member 103b through the lens 103a, and passes through the light receiving region 103d to be focused onto the light receiving surface of the light receiving unit 102a. The light receiving unit 102a then, performs photoelectric conversion on the focused light from the object, to generate an image signal of the object. Here, since the light blocking wall 103c blocks the light so that the light would not be incident on the region other than the light receiving region 103d of the cover glass 102b, the light receiving unit 102a receives only the light that comes from the object and enters into the barrel member 103b through the lens 103a. 